Method of making diaphragms



Patented Aug. 29, 1933 UNITED STATES PATENT" OFFICE j 1,924,316 mine, OF MAKING DIAPHRAGMS Jul-fen sgiiigh, oaklyn Manor, 'N. J.,"assignor to Westinghouse Electric & Manufacturing Come,

pany, a Corporation of Pennsylvania No Drawing. Application July so, 1930 Serial No. 471,751

' 2 Claims. L (01. 154 -2) My invention relates 'to cone-speaker diaphragms, or the like, and more particularly toa method of manufacturing thefsame whereby an increase in the speed of production andan im-y first the-preparation of a circular blank, then cutting or punching therefrom a sector. inthe form of a segment of the circle embracingapproximately a angle, and thereafterstitching M or glueing together the two edges of the blank thus formed. This method results in a product having a heavy stitched or cemented seamex tending from the apex of the cone to its circumference, thereby detracting measurably from the appearance and uniformity of the article.

More important, however, is thefact that, becauseof the time involved in the performanceof the necessary steps in the manufacture ofthe diaphragm, theabove method does not lend itdry process for manufacturing diaphragms.

Another object of my invention lies in the'provision of a simple and efllcient method'of producing cone-speaker diaphragms or the likewith a negligible amount of waste and loss.

for the manufacture of diaphragms according to my new method.

In acopending application of mine, Serial No. 468,830, filed July 18, 1930, I have set forth and described a method of manufacturing loudspeaker diaphragms of the cone-type which com prises slightly moistening a mixture. of paper pulp or the like and abinder having a certain amount of plasticity, and subsequently operating upon the mixture by means of, a die of a novel type so formed and constructed as to compress the mass into its desired shape. v V The present method to be described by me differs materially from the method described in the 7 Another object of my invention is to provide a method of preparing sheet material to adapt-it above, referred to application, in that the process is inherently a dry processl I In'the present process, one of my objects is to manufacture loud-speaker di'aphra'gms along the lines' followed in the manufacture of stamped metal ware, a procedureiwhich permits of rapid production of the desired article, T r

'Metals which permits of their being stamped and disk,

torted into various shapes :and configurations. '65 L This characteristic 'is'thatproperty of the metal which permits it toJflow or stretch under. the application of forces; of compression'or tension. The materials normally used in the manufacture 1 of cone diaphragmsghowever, do not possess this 7 desirable characteristic, and, consequently, so far as Ia'm acquainted with the prior art, no method a has been devised whereby diaphragms of the type mentioned can be manufactured by methods cus-fl tomarily applied' tometal articles,.wherein the article to be manufactured is produced'by flow ing or stretching the sheet material from which itismade.

The problem may be solved by imparting to at sheet of material to be used in theproduction of a diaphragm the characteristic of stretching or flowing under the applicationrof pressure. In the solution of the aboveproblem, a sheet of substantia'l'ly' non-flowable material; such as paper, cloth and the like, is operated upon to produce irregularities in its structure. :This may be doneby creping the materiaL'by which means we may condense the-flat sheet of material within an area smaller than that normally'occupied by. the uncreped sheet, in.wl ichncondition; the sheet is adapted tobe distortedinto: a plurality of shapes without tearing or destroying its homogeneousstructur'e. w I f P -.Crepe'paper ofthe conventional type is nor'rn'ally produced by creping the paper in one direction only, permitting a; specific flow in one direction' of approximately 69%. However, to'p'repare a blank sheet from which the diaphragms areto be punched, it will be necessary to crepe the blank in at least two different directions, so that the permitted flow or stretch of the paper or material inall directions will be substantially uni-. form.

It will be possible to obtain similar results by embossing the paper or sheet material'insuch manner that various figures, geometrical or, 0therwise, appear on both sides of the sheet. 'It

will be apparent that sheetmaterialembossed in the'manner described will possess the desired quality whereby,'by means of suitable dyes, these inherently possess-a characteristic sheets of material may be distorted into the desired shapes.

As an alternative method of preparing sheet material to impartthereto the characteristic of flowing under. pressure, the sheet may be modified the corrugations will not be completely, ironed out. .This possesses the advantage of imparting .to the final diaphragm a greater stiffness against paper rattle, thereby making unnecessary the concentric embossing usually employed in the manufacture of cone diaphragms, after the diaphragms have been formed.

Before the blank sheets of material are creped, they should have approximately the thickness desired in the finished diaphragm. The creped paper, known in the prior art and referred to heretofore as being creped .in one direction only, besides being unsuitable for loud-speakers, because of its uni-directionally creped characteristic; also is not of the desired thickness, this paper having a thickness of approximately 3 mils when uncreped. The material to be used for diaphragms should have a thickness at least twice 7 as great and should be creped lIlISllCh manner as to permit a flowof approximately 40%. in all directions.

, Itwill be possible, however, to utilize a plurality of thin sheets super-imposed one upon an-'- other. to produce a sheet of therequired thick, ness. Between the various layers, a suitable binder may be employed to unify the sheets into an integral structure, the addition of an adhesive 1 binder or some suitable sizing material being 7 into its finished form, heat may be applied in any suitable manner to bring about the unification of the various layers of material.

The various geometrical configurations .imparted to the substantially fiat sheet material prior to distorting the same into the shape of the finished productmay or may not b'e of such depth as to becompletely ironed out during the distorting process. By making the configurations of sufficient depth, it will be possible to produce a diaphragm, the surface of which will be covered by any suitablegeometrical design, thereby improving the appearance of the finished article.

. Throughout the above description, I have used the expressions creped or creping in a generic manner as applying to all sheet material A which has been condensed within an area less than that ordinarily occupied by the sheet.

In lieu of the creping operation for imparting non-flowable material, I consider it within the scope of my invention to produce a suitable materialof fibrous'nature, the fibres of which have such characteristics either because of their length or the manner in which they are intermingled,

that the material may be stretched or caused to flow, under the application of pressure, without being torn or otherwisedestroyed.

After the distorting operation necessary to give the final shape to the material, the resulting product may be protected against atmospheric influences by applying thereto a finish having the desired properties. Aeroplane dope or pyroxylin lacquer may be suggested as materials having such properties as to afford protection to the dia phragm against atmosphere influences: The process disclosed-by me above does not employ the use of wet or moist material. It is a dry'proc'ess from beginning to end, in view of which the time required to produce a finished article'is materially shortened. The diaphragms are adapted to be punched from sheet material in much the same manner as the methodzused will be apparent, therefore, that the objects of scribed above.

Various modifications may be made within the scope of my invention which may have a wider field of application thanthat described above. While I have disclosed myprocess as applied to the manufacture of loud-speaker diaphragms, the same process may be employed in the manufacture of non-related articles, such as paper boxes, novelties, and the like which may generically be described as dished receptacles, whereinthe shape of the completed-article is such as to'permit of being punched and pressed intocompleted form from a substantially fiat sheet of material. I, therefore, do not desire to be limited to the details disclosed above, except; insofar as is necessitated by the prior art and the appended claims.

I'claim as my invention:

1. The method of making a dished article which comprises preparing ablank of substantially flat material, creping said blank in at'least two directions to acquire the property of flowing substan tially equally in all directions under the application of pressure and subsequently distorting said blank into its desired form.= I

. 2.:The method of making a dished article which comprises creping a substantially fiat sheet of material in at least two directions, maintaining said sheet in a substantially dry condition and subsequently distorting said sheet into its desired form.

. 'JURJEN S. HIGH.

"so the fiow characteristic to a sheet of. otherwise 7 for quantity production of metallic articles. It I 

